The present invention relates to an objective changing-over apparatus, applied to a microscope or other optical instruments, for selecting an objective of desired magnification, according to the object of observation among a plurality of objectives, and positioning on the observation optical path by electric power.
Conventionally, in this type of apparatus, the revolver movable section is rotated by driving a motor with a predetermined voltage, and the rotation of the revolver movable section is stopped by placing a mechanical engagement mechanism between the revolver movable section and the fixed section. This engagement mechanism mechanically engages, positions and holds the revolver movable section and the fixed section, each time when the optical axis of the respective objectives attached to the revolver movable section comes to a position in agreement with the observation optical path of a microscope or other optical instruments.
FIG. 34 shows the configuration of a click mechanism which is an example of engagement mechanism applied to the conventional objective changing-over apparatus, and FIG. 35 is a view along X of FIG. 34. In this click mechanism, a ball 203 is fixed on a leaf spring 202 provided on a fixed section 201, and triangular pyramid shape engaging holes 206a, 206b are provided on the revolver movable section 205 with objectives 204a, 204b. The positions of ball 203 and engagement hole 206a, 206b are adjusted to a height generating a stress in the leaf spring 202 when the ball 203 is positioned at the engagement hole 206a or 206b. Thus, the position of the revolver movable section 205 is reproduced by introducing the ball 203 into the engagement holes 206a, 206b by the elastic force of the leaf spring 202.
Moreover, for example, Jpn. Pat. Appln. KOKAI Publication No. 5-281457 discloses an apparatus that can be used as microscope revolver rotation apparatus or the like, for driving a revolution body (revolver movable section) with a plurality of objectives, and for disposing each objective selectively at a reference position. This apparatus outputs a motor stop signal when motor stop state is detected by a sensor, and after the motor stop signal is output from this sensor, detects the suspension of motor stop signal from the sensor after a predetermined time by a transmission type sensor, and rotates the motor for a very short time by an electronic control circuit.
In the aforementioned conventional apparatus, mounting state of objective to the revolver movable section (quantity, type, attachment position) is different according to the user operation conditions. Consequently, as the load to the motor driving the revolver movable section also changes, it is difficult to perform an optimal motor stop control.
Besides, as the motor or driving section, and the revolver movable section are connected without clearance, the motor stop position is required to be precise. Therefore, a delicate adjustment is required for means of electrically detecting motor stop position, and a complex control is required for braking means of motor driving source.
Repeated use provokes abrasion, resulting in worse position reproductively or leaf string damage, because the click mechanism is deprived of sliding between leaf spring and ball.
As for the swing type objective changing-over apparatus (revolver) presenting an improved manipulatability for marking abnormal sites on a sample, a large force is required for regulating the rotational force and keeping the position, as the objective retracted from the optical axis makes an angle of about 60 degrees with respect to the optical axis, while the click mechanism requires a large clearance and, in addition, provokes a big impact during the positioning.
The present invention has an object to provide an objective changing-over apparatus of simple configuration, that can be assembled and adjusted easily, for securely performing objective changeover with a simple control, independently of its mounting state variation.
The objective changing-over apparatus of the present invention mounted on a microscope, for changing over two objectives on the microscope optical axis by electric power using a driving source comprises a rotation member to fit the two objectives, and two abutting members for limiting the rotation range of the rotation member, a transmission mechanism having a rotation area including a transmission area for transmitting the force and larger than the rotation range of the rotation member limited by the abutting member, for transmitting the force from the driving source to the rotation member by the transmission area.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.